1. Technical Field
This application generally relates to a computer system, and more particularly to obtaining configuration information and executing a call within the computer system.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as the Symmetrix™ family of data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more host processors and provide storage services to each host processor. An example data storage system may include one or more data storage devices, such as those of the Symmetrix™ family, that are connected together and may be used to provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. Such storage devices are provided, for example, by EMC Corporation of Hopkinton, Mass. and disclosed in U.S. Pat. No. 5,206,939 to Yanai et al., U.S. Pat. No. 5,778,394 to Galtzur et al., U.S. Pat. No. 5,845,147 to Vishlitzky et al., and U.S. Pat. No. 5,857,208 to Ofek. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data stored therein.
A host may issue a call to a data storage system, such as the Symmetrix™ data storage system, requesting configuration information. Such configuration information may include, for example, data regarding the availability, status, or other attribute about the data storage system, or a resource therein. The host may subsequently take an action in accordance with the configuration information received. A problem may arise if a change in the configuration information occurs between the time when the configuration information is returned to the host, and when the host takes the action. The change may cause the configuration information received by the host to become outdated or otherwise inaccurate. As a result, the host may not be taking the action in accordance with correct state of the data storage system as may be represented by the configuration information. Additionally, the host may issue multiple calls to obtain all the configuration information such that overhead associated with multiple calls is incurred increasing the amount of time between when a query is made by the host and when the host's action is taken.
It may be desirable to provide a technique for efficiently obtaining information, such as configuration information, from a data storage system. It may also be desirable that this technique provide for reducing the amount of time between when information is requested, and when an action may be taken in accordance with the information. It may also be desirable that the action be taken in accordance with a specified condition such that, for example, if a configuration has changed since a query request, the action is not taken.